The victory in Guadalajara, Mexico, was the 10th WTA title of Muguruza’s career and her third of the year.
Having collected grand slam titles at Wimbledon and the French Open in 2016 and 2017, Muguruza — who rises to No. 3 in the world off the back of the victory — suffered a dip in form and dropped down the rankings over the next two years.
But she now looks back to her best and proved too strong for Kontaveit in Mexico.
“I’m just very happy I proved to myself once again I can be the best, I can be the ‘maestra,’ like we say in Spanish,” said Muguruza. “That puts me in a very good position for next year, a good ranking.”
Muguruza and Kontaveit exchanged early breaks in Wednesday’s final before Muguruza broke again to take a 4-3 lead and wrapped up the first set with an exquisite backhand lob.
Estonia’s Kontaveit, now No. 7 in the world after reaching the final, gained the initiative in the second set and looked on course to level the match as she built up a 5-3 lead.
However, Muguruza secured two breaks across four games as she sealed the title.
“Right now, I feel extremely happy and relieved because it’s a tournament that I’ve struggled at the beginning, then I managed to play well,” said Muguruza, who started the tournament with a defeat to Karolína Plíšková and then had to come back from a set down to beat Barbora Krejčíková.
Muguruza’s victory means the WTA Finals, which were canceled last year amid the pandemic, have produced six different champions over the past six editions of the tournament.